[GAMEPLAY?] Disappearing LP

I apologize now that I don't have screen grabs. I realize now I should have taken some, but whatever.

So I'm at 0LP in Silver 5. I win a game and it gives me somewhere between 10-15LP, I don't recall the exact number, but it was definitely above 10.

I win a second game, and where it lists the LP it shows me: 26LP (+20LP).

I didn't lose a game between the two.

So, either the game deducted 5-10 LP from me at some point, for an undisclosed reason, before adding the 20 new LP. Or, the unit that shows the increase in LP misreported the number, in which case I would have only gotten 10-15LP more in the second game, which seems rather low for a second win in a row.

Thoughts? Is it just my imagination?