I had 3 bottle bombs last weekend(6/29/13) on two different batches of beer that were both bottle on 4/20/13.
Both batches were 5 gallon extracts. One was a cherry wheat 2 bottles exploded and the other was a milk stout and one bottle exploded
Both were bottled with 5g of priming sugar, rack on top with siphon on very bottom of bottling bucket and then gently stir. Bottles were kept at 70 degrees for 3 weeks in dark room and then stored at 35 degrees until 6/22. I moved 6 bottles of each from a walk in cooler kept at 35 degrees and moved to a cooler with ice on 6/22. I only drank 3 of each on 6/22 and moved remaining 3 of each back to the cooler that night. I then moved the last 6 from the walk in cooler to another cooler with ice on 6/29 and the bombs went of in the cooler.
The car ride was not bumpy and the beer were not vigorously shaken at all during the transfers but the cherry wheat a couple that were pretty carbonate on 6/22.
All other beers were evenly carbonated in both batches except 3 on 6/22.
Not sure why this happened but I want to make sure I don't give away any future bottle bombs
Keep calm and brew on.