The problem is that other months, most of them run deficits.
You do understand this is just one month out of twelve, correct? At the end of the fiscal year, the US will have another handsome deficit, so don't get too excited.
The government always has a surplus in April. Always. That is when the tax returns are due and people pay their tax bills. There is nothing new or unique about this.
...
True, but the article says a deficit was expected, so this is a big difference. Year to year comparisons for the same month can also be informative.