i drive a 1991 honda accord with 265k miles.

a couple of weeks ago i 'flushed' my transmission (read: changed the fluid 3 times in a row). it cleared up a rough shift from 1st to 2nd, but now when i'm coasting (take my foot off the accelerator) it no longer shifts up to a higher gear. at first, it hesitated a bit before upshifting, but now it doesnt do it at all.

one thing i had noticed was that before working on the transmission, it was a bit overfilled. now it is right at the halfway mark. would this make a difference? i used honda atf. i also recently put in new plugs and air filter. cant think of any more info. should i be worried? as far as i know it is the original transmission and i have no other problems or complaints. any info would be appreciated, thanks!!