Hi Jack, Hi Guys,
Jack, you don't state how old your watch is.
Omega have made many many diferent Seamaster chronographs over the years. some have hand wind mechanical movements ( eg 320, 321 or 861), some have automatic mechanical movements ( eg 1040, 1045 ) some have quartz movements ( I don't know those movements.. sorry ) & the more modern ones have the 33xx range of movements.
I haven't heard of the problem you're describing happening with a modern movement. It DOES happen with some of the older movements especially the 861 movement. I'm not sure if it is the official term, but on the various forums it is called "chrono creep". I'm not a watchmaker, but I understand it is not a serious problem. I have a Speedmaster that sometimes does this. I usually press the reset buttom before starting the chrono.
I'm not going to send it to my watchmaker just because of this, but will get my watchmaker to look at it whilst it's having its next service.
I realize that not everyone has the same attitude, & whilst it's annoying that you pay for a service which isn't upto the standards you expect, I'm just trying to say that "Chrono Creep" does happen with some older watches & it's not a serious problem.
I hope I've helped a bit.
Steve