Yes, that happens to me too. I've found that there are just some times when being on SR isn't helpful. I either get overwhelmed by how reading how much of a struggle it really is, or reading a post might bring up a fun memory of drinking. Those times I just realize I need to take a step away. There have been many more days where I needed to be here, and got a huge benefit from what I was reading. I also notice that some days I can do replies and give support and others I don't have it in me.
If you can hang on to any good experiences and focus on how you're feeling it's a great tool for remembering why you want to be sober in the first place.
Often, it was great because you were experiencing it with a clear head and were able to fully feel the emotions. It feels like a gift that sobriety has delivered.