mercedes 190E 2.6 1991 130,000 miles

I recently rebuilt the automatic trasnsmission myself, it was not working at all. I cleaned it and the cooler out very well at the time. Now it starts out in first gear, stays there until about 25 MPH and skips second directly to third. If I accelerate pretty hard, it kicks down to 2nd no problem. All of the up shifts and down shifts are nice. I replaced the hard seal around the B1 piston when I did the rebuild and I felt it was harder to move it in and out of its bore afterwards. Is this the problem, or where should I be looking?
Thank you,
Sean.