Small amount of blood in the litterbox

My girl Dali seems to be passing a couple drops of blood in her stool. I think this has happened about 3 times in the past 2 weeks. I noticed something weird when I saw a bit of blood on the floor, but at the time it was dry and I mistook it for a bit of food. I confirmed what it was recently when she had an accident while she was in my room longer than usual. Her stool looked normal, but there was a bit of bloody mucous.

I don't think she's straining when using the litterbox, but I'm looking out for it. I've checked her a couple times to see if she has any blood back there, but there's been none.

I'm planning to take her to the vet soon(I don't have a lot of money right now), since she's nearly due for a checkup.

Has anyone experienced this?

Some other details:

No big behavior or weight changes. The only change I've seen in the last 3-4 weeks is that is that she paces herself a little more when eating. I feed her Rachel Ray dry cat food and she's eaten it regularly for several months now with no trouble. She stays hydrated, and there's no change in frequency of litterbox use.

She's indoor only but the neighbor's outdoor cat was in the house briefly one night(it was below freezing outside and I brought him in until his owner got him). They didn't interact since I separated them.

Edit: I forgot to mention she's been having some gas since about a month ago. Not often, but it'll happen maybe 3 in 10 times when someone picks her up.

Is the stool super hard, and in little separate chunks? If she's constipated, that could be the reason for the blood. This may sound gross, but you may want to Google "cat stool forms" and see if she is constipated.

Definitely a trip to the vet too, just to be sure

Her stool hasn't been hard or segmented, it's been pretty much the same, with the mucous being the only unusual feature. Still going to try to observe her for any straining though.

Thanks for the advice!