no, your don't "lose" your Tourist Visa. you're given a 60 day permission to stay and as a result the visa sticker in your passport is stamped "USED". The 60 days will be indicated by a stamp in your passport which can be on a different page to the visa sticker.
you can extend that 60 day permission to stay once, for a further 30 days.
I'm assuming you used the new e-visa system and had a printout of it with you. The officer taking that printout from you is, I suppose, the equivalent of the old USED stamp as described above. Plus he'll make a corresponding note in the immigration database.
Look in your passport for the 60 day stamp. That will show you the exact date up to you are permitted to stay in the Kingdom.