Can you still get positive tests after 10 minute mark?

mommabear
I took a first response pregnancy test two days ago. I checked it as best I could (the new stupid curve handle makes it so hard) and I saw a faint line when I looked in bathroom lighting. I kept the test just in case. I checked it a few hours later and the next day (so, yesterday) and the test looked like this. Should I retest or was it just an indent?