Evap lines

Mariel

So, I have purchased this brand of tests many many times, and I have never gotten/seen evap lines before. I took a test last night and didn’t see a line within the time frame, so I left to go to a bbq and came back to a line. Took another test and the same thing. No line, then woke up to one. Does anyone know if these tests are known for evap lines or could they really be late positives? Going to take another test today, but just curious. Thank you!