A pay raise?

I just signed the second of my revolving four-month contracts. (They can't put me on a full year because then I would be eligible for benefits...!) I was a little surprised to notice that my monthly payments increased. I'm not entirely sure if this is a pay raise, but it sure looks like it! One of the more confusing factors is that my salary is not completely stable ... I make slightly different amounts each month (differing by almost 50,000 pesos per month, or about $100), and I receive my paychecks on random days of the month (usually in the 3rd week, but occasionally the Friday of the second week...) I guess there's always the possibility that I'll hear from one of the secretaries of a random gap in payments (i.e., "We paid you more the past four months because we aren't paying you in X month", or something like that). But there remains the possibility that this is a genuine payraise. Stay tuned!