Galaxy S6 new fingertouch not safe / not working properly?

A

AC Question

Yesterday a friend could unlock my S6 edge a couple of times with his own finger. Messed with it for + 1 hour and did it exactly 5 times...
Of course his finger is not reg! Then my daughter managed to unlock my S6 just 1 single time this evening - but couldnt do it again even though we tried for almost half an hour. Anyone else experienced problems with the fingerprint / fingertouch function on S6 or S6 Edge?