Likely not, unless it's been positively identified as something like powdery mildew, which no one wants to intentionally bring that into a garden. But being grass clippings, I myself wouldn't worry about it. Mold is evidence of bacterial and/or fungal decomposition.
"Study books and observe nature; if they do not agree, throw away the books." ~ William A. Albrecht
I don't know what sort of mold you're seeing, but I've seen two types...
...the black slimy mold in mucky, wet clippings that were let to sit while overly wet. This mess is difficult to work with, but I've used it in gardens with no negative results.
...the white mold that rapidly grows in fresh clippings that sit in a pile overnight or for a few days. Because I often mow grass one day and apply it a couple days later, I encounter this mood all the time. It has never hurt my plants. BUT I do need to be careful not to apply hot clippings around the stems of the plants. They heat itself can damage them. Simple solution- spread out the clippings pile for a few minutes to let it cool before using.
That white mold is a normal part of soil biology. It is normally found on the soil surface. In clippings and hay, it only needs a bit of moisture to start replicating and going to work.
It's never too late to start! I retired to homestead on the slopes of Mauna Loa, an active volcano. I relate snippets of my endeavor on my blog : www.kaufarmer.blogspot.com
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