He was stretching out his right quad after walking the first batter. After the second batter, the trainer and coach came out, and it seemed like Logan was insisting to keep pitching. He threw a few warm up pitches and then faced the next batter, and didn't seem to be struggling/laboring at all. As soon as he got that batter out, Sweet came out immediately to replace him.
Didn't seem like anything too serious. Seems like he may have tweaked something, and then they let him face one more batter (to reach a pitch count?), and then took him out as a precautionary.