Invalid and/or missing SSL certificate

I'm trying to build a datastore on Google App Engine to collect some stream data off of StockTwits for a bunch of companies. I'm basically replicating one I did with Twitter, but it's giving me an HTTPException: Invalid and/or missing SSL certificate error for one of the URLs. I changed the URL to look at another company, but got the same result.

Here's the code that pulls the data:

class StreamHandler(webapp2.RequestHandler):

def get(self):

    tickers = ['AAPL','GOOG', 'IBM', 'BAC', 'INTC',
               'DELL', 'C', 'JPM', 'WFM', 'WMT', 
               'AMZN', 'HOT', 'SPG', 'SWY', 'HTSI', 
               'DUK', 'CEG', 'XOM', 'F', 'WFC', 
               'CSCO', 'UAL', 'LUV', 'DAL', 'COST', 'YUM',
               'TLT', 'HYG', 'JNK', 'LQD', 'MSFT',
               'GE', 'LVS', 'MGM', 'TWX', 'DIS', 'CMCSA',
               'TWC', 'ORCL', 'WPO', 'NYT', 'GM', 'JCP', 
               'LNKD', 'OPEN', 'NFLX', 'SBUX', 'GMCR', 
               'SPLS', 'BBY', 'BBBY', 'YHOO', 'MAR', 
               'L', 'LOW', 'HD', 'HOV', 'TOL', 'NVR', 'RYL', 
               'GIS', 'K', 'POST', 'KRFT', 'CHK', 'GGP', 
               'RSE', 'RWT', 'AIG', 'CB', 'BRK.A', 'CAT']

    for i in set(tickers):

        urlst = 'https://api.stocktwits.com/api/2/streams/symbol/'
        tickerstringst = urlst + i + '.json'
        tickurlst = urllib2.Request(tickerstringst)
        sttweets = urllib2.urlopen(tickurlst)
        stcode = sttweets.getcode()

        if stcode == 200:
            stresults = json.load(sttweets, 'utf-8')
            if "messages" in stresults:
                stentries = stresults["messages"]
                for stentry in stentries:
                    sttweet = streamdata()
                    stcreated = stentry['created_at']
                    sttweetid = str(stentry['id'])
                    sttweettxt = stentry['body']
                    sttweet.ticker = i
                    sttweet.created_at = stcreated
                    sttweet.tweet