My dog acts afraid of me after playtime

I have an almost 2 yr old red nose pitbull mixed with boxer and lab (possibly?) who is the sweetest, most playful thing you ever met. My wife and I take turns playing with her twice a day, once in the morning and once in the evening after we get off work. We have to play with her like that because she has an extremely high energy level.

Anyways, yesterday evening I was doing the evening play routine as usual. Her play routine consists of me kicking a chewed up Sumo ball around the around. I kick it and she fetches it and brings it back to me every time. We do this typically until she starts slowing down because she, left to her own decision, will not stop playing because she loves the game so much. However, yesterday I kept going after she slowed down because I could tell she still wanted to play. I did this until she just wouldn’t go after the ball anymore. I brought her inside, gave her water, let her cool off for a while before feeding her. I could tell she was more tired than usual and she didn’t eat much food, but other than that she seemed fine.

Today, before work I went out there to play with her. She was excited as she usually is but this time when I went to kick the ball, she just stood there. I went to fetch the ball myself and she followed me to it and I kicked it again. This time she tucked her tail between her legs and went and hid in the corner of the yard shaking. She would not approach me and acted like she was afraid of me. Then she ran to the door and wanted inside. I let her in and inside she seemed fine. Indoors, she will come up to me like normal so I can pet her and lay next to me, etc.

So this evening, I attempted to play with her again. She did the same thing as this morning, but not as bad. My wife went out there with her and she played completely normal. I tried to kick the ball once in the middle of their game and she looked like she wanted to run and get it, but she didn’t. So my wife ended up playing with her tonight.

I should probably note that we live in Texas and it was a little warm yesterday before all that rain came in overnight and cooled things off. To anyone with insight into this or having experienced something similar, I welcome your feedback and comments.