Strange (to me) entry in my wallet

when i do “grin wallet outputs” there is a line i do not understand, it is a commitment of 60.008000000 for “mining”

when i first saw that i thought i had found a block
unfortunately no

I first saw that yesterday and did a “grin wallet check” and after resynching the wallet, that 60 grin comiitment went away. Since then another entry for 60 more grin has reappeared.

I haven’t mined any blocks yet, i was wondering why that line is in there?