I filed January 28th. It is now March 5th and I am still receiving the "it's being processed" response. Should I call the IRS to make sure everything is okay?

You can If you are concerned and it's been over 21 days since your tax return was accepted are some tips when contacting the IRS at 1-800-829-1040. Do expect long wait times during the filing season:

• First choose your language. 
• Then do not choose the first choice regarding REFUND, or it will send you to an automated phone line.
• Instead, press 2 for personal income tax questions.
• Then press 1 for form, tax history, or payment.  
• Then press 3 for all other questions.
• Then press 2 for all other questions to be transferred to an agent

Also this TurboTax FAQ lets you know what to have ready before you contact the IRS: https://ttlc.intuit.com/community/irs/help/what-do-i-need-if-i-call-the-irs/00/27378

Here is some information on why refunds take more than 21 days:

• Why do some refunds take longer than others?