2000GrandAmGT34

I'm having a slight issue with my overdrive it slips and grabs when I apply a bit of gas to accelerate but I noticed it generally happens when it's warm or hot outside for the past 5 years. I hadnt noticed the problem in colder weather it generally would do it going home. Do i have a problem with temps? The transmission shifts fine otherwise. I started noticing it after a year of changing the fluid and filter. Oh it's a 2000 Grand Am GT 3.4L. With about 122k miles.