Auto Trans serviced, now slipping!!

[ridgerunner]

Have loved my '98 318ti since I bought it over 2 years ago. GREAT balance, comfortable, well-mannered, fun, etc. Sad part is I drive 40-50k miles a year and now have over 150K on the car.
My Service Center (finally gave-up on the dealership) earnestly suggested an Automatic Trans service was in order. Tranny was functioning perfectly, NEVER abused, but never had been done sooo...okay, sure, go ahead. As soon as I picked it up I detected an intermittent slip. So intermittent, in fact, that the neither the Service Writer or the Mechanic (or I at the time) could make it slip again when I immediately took it back.
Now, it occurs usually at the first stop & go from a cold start-up (at slow neighborhood speeds). It's a quick "free-spin" & then catches hard. It seems to diminish as car warms-up. So far, it's unnoticeable at higher speeds.
Question is...has anyone ever experienced a Auto Tranny Service that seems to have generated a mystery slip? The level is correct. Could my guys have used the wrong fluid? Do I have a "bubble" somewhere. It's so damn inconsistant that I'm hoping it's correctable. Or (gulp!) is it just weird timing & I need to be saving my money to replace a soon-to-be expired transmission?
Thanks for your help. I can tell you from experience that BMW owners are the best out there!

Ridgerunner

[95white318ti]

Exact same thing is occuring with mine. is it just from the cold?

[bmvw]

Mine does that when it's low. I would take it back and have them check the fluid level.

[95white318ti]

Hmmm. I'll have it checked out. I had it filled when it was changed, then a few days later I had it topped off. So I cant imagine that it's low.

[familytruckster]

Filling these transmissions is a PITA. The trans has to be a a very specific temperature.
Which is about 85*, so if you drove the car there and they checked it it would probably be too hot. It's more of a drop off overnight check it in the morning type of job.

Also, with that kind of milage servicing the trans usually isn't suggested because it can loosen up sludge and clog everything up. Most places will not service the trans with that kind of milage without having you sign a waiver.