Such a petty offense, who cares if they bought toothpaste instead of lunch if they're within the budget allowed.. it's not like they're gonna waste it.
I think they sent a warning about it and if you continue you'd be reprimanded. That being said, I swear this must be more of their "cost-reduction". Like you said, it's within budget ... I can imagine finding replacement employees and hiring is more costly than this by far.