Husband acting strange

So usually my husband is moody because he doesn't like his job, always complaining about money(even though we're comfortable and not living paycheck to paycheck), and NEVER wants to have sex. Well, the past couple days hes been talking about buying a new $15,000 truck from his brother, has been super nice and joking around with me all the time, and has been wanting sex a lot more(We had sex 2times today within 4-5 hours, we've never done it more than once in a day). Just dont know if I should be concerned or not...