Another reason to consider opening another card has to do with what's called credit utilization. Utilization measures how much of your credit you are using in relation to your total available credit. If you have one credit card with $500 charged to it and a credit limit of $1,000, then your utilization is 50%. There's no ideal utilization to shoot for, because as with most things, it depends on everything else on your report. But as a general rule, you want to try to keep your utilization on any one card, and across all of your credit cards, below 50% to avoid the risk of hurting your FICO® score. Research has shown that people who max out a single credit card are more likely to miss future payments, and therefore the FICO score considers people using more of their available credit more risky than people who are using very little of their available credit. http://www.myfico.com/crediteducation/questions/credit-card-management-help.aspx
can't find the related documentation for 70% but I beleive i have seen it in the past, where creditors count cards over 70% used as maxed out, But the above comes close.
What are your CLs and balances?