Would you think, childcare is exhausting and now they could use a break as well, or would you think that they are putting on a show of how tired they are, because they actually resent the fact that you took a break in the first place?
Wow it would be really pathetic and paranoid to make the assumption that they are being passive aggressive or resenting your break.. Raising kids, especially with no help IS exhausting.. There's a reason why generally speaking it takes two parents to raise kids.