Credit increase ?

It's most likely your income level and how often you use the card. You say it's not a "need" card, so why do you "need" an increase?  Creditors don't always give you an increase based on your score--it's also your ratio of how much debt you can carry safely to what you make. 

Your overall credit line (all credit cards) is calculated in the algorithm to determine if it is smart to give more credit. Example: If you have 3 credit cards and each has an open credit limit of $5000 then your POTENTIAL debt ratio may be too high (15K) for your income (doesn't matter if you even use the cards the potential is there). 

Get a credit report from one of the credit reporting companies (you are allowed on free per year) and see what they have on you. Close some accounts that you don't use and try again in a few months after making the adjustments.  

I had the opposite problem every credit card company kept increasing my limit until I had 15K of credit on two different cards - keeping my credit score in the high 700s, Reduced the limit on both cards to 5k each and I bounce around in the 820-849 credit score regularly.

OR

With a 795 score sign up for another card with higher limit and cancel the card from the cheap bastards who are turning your down.

Score of 795 is great.  But how much you are allowed to borrow depends on multiple criteria including your income.

Most likely your income doesn't support a higher credit amount.

It can simply be that they have hit their lending budget for the month and can't lend any more for now, to anyone. They don't ever say why though but it could be that. Or some people get denied credit by a computer online, they appeal and then they get it. You can write and appeal incase a computer made the decision wrongly, then a person looks at the application and may change the decision.

The credit limit probably depends on your income. 

No one has to extend credit to you.  And they don't need a reason to refuse.