draftkings alternate spread showed -2.5 but slip accepted -3.5 somehow

so i was looking at nba alt spreads and it clearly said -2.5 for the favorite, and when i hit place bet, the slip that went through locked me in at -3.5 instead. double checked right after, the display still said -2.5, but ticket says different and now i need the team to win by four. i’m always triple checking those numbers because of variance but this time i swear it wasn’t my mistake. not the biggest deal but it’s annoying since i play conservatively with spreads most nights, almost never go past -2.5 or -3

has anyone else had this happen? is this just some bug when lines are moving, or did i miss something with how alt spreads recalculate? not my first time catching a weird thing on these slips but this is a new one for me. any tips for stopping this happening again?