The serial blasts in Ahmedabad and Bangalore have not only disrupted normal life in those two cities but has upset the unfailing punctuality and precise timing of Mumbai's dabbawalas which has earned them a six-sigma performance rating from Forbes and acclaim from across the world.The timing of dabbawalas took a hit for the first time in years on Monday when random checking of their tiffin boxes by Government Railway Police (GRP) at CST and Churchgate — the two main spots where tiffins are sorted out — and other stations resulted in dabbas reaching many patrons almost half-an-hour late.The GRP began checks on dabbas on Monday morning after it was revealed that two of the 17 bombs that went off in Ahmedabad on Saturday were placed in tiffin boxes. The same modus operandi had been used at the time of the Jaipur blasts in May this year.Sapan Mare, president of Mumbai Tiffinwala Association said the checks resulted in a "little delay."Mumbai's dabbawalas deliver around 2 lakh tiffin boxes containing home-cooked meals to office-goers every day. The network of nearly 5,000 workers relies almost entirely on local trains and takes pride in its 125-year-old tradition of delivering each and every tiffin on time."I understand the police are only doing their job, but if such checks intensify, we are bound to get late with deliveries as every minute counts," Mare said.However, Dilip Mane, senior inspector of CST GRP, said they could not leave anything to chance. "Other than tightening our security-checking measures, we have also focussed on checking random dabbawalas. So we stop an occassional dabbawala and take a quick check of his dabbas by asking him to open his tiffin boxes."Mane said he was aware of how important time was to dabbawallas. "We don't mean to inconvenience them in any way, so we conduct our checks in a flash and relieve them quickly." M D Raskar, senior inspector of Churchgate GRP said not only dabbawalas, they had also decided to check tiffin boxes of commuters whose movements might appear suspicious.But the dabbawalas are keen to retain their track record that says they make one mistake in every 60 lakh transactions.Raghunath Medge, president of Nutan Tiffin Box Suppliers Association, said they had served Mumbaikars for three generations, with an emphasis on punctuality. "We can't get late as any delay will upset our customers. We have a foolproof system in place, so with police now checking tiffin boxes randomly, we get harassed. Metal detectors are great, but we are against opening our dabbas during checks as opening and closing several dabbas consumes time. Our dabbas are duly coded and marked and we never can let any alien tiffin box to enter our chain of deliveries."Patrons too are worried. Ziauddin Ansari, a store manager from Crawford Market, said, "I've been using the dabbawala service for the last four years, and my tiffin has reached me at 1 pm every day. On Monday, I asked the dabbawala what got him late. He said cops had checked him thrice while on way to my place." Meenaxi Tiwari, an accountant who works at Nariman Point said, "I was awaiting lunch from my Borivli home at 1 pm as usual but received it at around 1.25 pm. The dabbawala had to undergo a security check at Churchgate railway station, which got him late."