Indent line back to back? (No Pictures)

Hello, I tested yesterday and a very faint line showed up. I tested this morning again and the line is darker than yesterday, but still very faint. I took a third test (thinking if I don't get a line on this one then the rest is all an indent line) and another faint line came up. Is it common to get indent lines three in a row with three different pee? They all showed up within the time limit, so I don't think it's a evap lines.

I'm using pregmate test strips. I bought it because I was going to track my opk, and I've been using some of the pregnancy test strips it came with. It never showed any indent lines just a very clean BFN. So, it kinda of tripped me out when 3 test strips had lines back to back.