1/2 qt over is the problem, though I bet it is higher than that. I would siphon a little out. Any time mine has been even a touch over full, there are also some bubbles on the stick. So that proves that it is foaming when over full, which is not good.
You should not need a great seal at the dipstick because it should not be that full. So if anything, it leaking out there is helping you get rid of the excess. Siphon some out before you damage something.
That guy is no transmission expert. Anyone knows how important proper fluid level is, and he should have siphoned an equal amount out first. Durrh!
97 T-Bird LX 4.6 - 80k miles
94 Supra TT Auto - street/strip car
04 CVPI- Brenda's car - 76k miles
95 T-Bird LX 4.6 - fully optioned, owned 15 years, 220k miles
96 Cougar XR-7 4.6- Brenda's car, owned 11 years, 187k miles
88 T-Bird 3.8 - first T-Bird, owned 5 years, 206k miles