It's totally natural for small style shifts to happen over the lifespan of a comic, something that I would be more concerned about is MAJOR style shifts, there was this one comic that I had read a long time ago called Olympus Overdrive. I think it was a hiveworks thing, anyways, the artist drastically changed their style every couple of chapters, one chapter may have had a serious semi-realistic marvel-esque style, then the next would be a more anime influenced style, then the next had a cutesey homestuck-esque style. It was really jarring and I eventually stopped reading it because I felt like the creator didn't really have a clear vision for what they wanted the comic to be.
For me personally I've been working on my comic for 3 years now, and I restarted my comic from scratch twice, partially because I felt like my style had changed too much between the gaps of working on the comic. It's not as big of a deal if that shift happens gradually, but I hadn't been able to work on the project consistently. On top of that I kept rewriting the story, and as the story developed more and more I felt like whatever the previous styles that I had used no longer properly represented the tone of the story I was going for. Also some pages were cringe-worthily bad and I was super embarassed by them.
Here are the different covers I've done for the project as examples of what I'm talking about I guess.
TLDR. It's not a problem if your style changes gradually, but changing the style significantly all at once can be disorienting.